1. Field of the Invention
The present invention relates to a person retrieval apparatus for retrieving a person, who is similar to a person taken by, for example, a camera from registrants stored in a dictionary.
2. Description of the Related Art
Conventionally, a person retrieval apparatus retrieves a person similar to a person taken by a camera from a plurality of candidates (registrants). Some person retrieval apparatuses retrieve a person based on the similarity in biometric information of the person. For example, in the person retrieval apparatus for searching a person based on a face image as the biometric information, a person similar to a person taken by a camera is specified from a plurality of registrants on the basis of the similarity between facial characteristic information obtained from an image taken by a camera and facial characteristic information of each registrant registered in a dictionary.
There are proposed various types of apparatuses for identifying the facial characteristic information. For example, Jpn. Pat. Appln. KOKAI Publication No. 2005-53385 discloses a walker authentication device for acquiring facial characteristic information from an image obtained by taking a walking person (walker) to collate the obtained facial characteristic information with each facial characteristic information registered in a dictionary. Meanwhile, Jpn. Pat. Appln. KOKAI Publication No. 2005-100369 describes means for extracting facial characteristic information of a person, who is a target to be authenticated, on the basis of a plurality of images taken by a plurality of image pickup means. Jpn. Pat. Appln. KOKAI Publication No. 2005-100369 discloses to narrow down both a region to be processed and candidates to be searched, and to perform image correction in accordance with determination of an image quality.
However, in general, in a system for retrieving a person based on face images taken by a plurality of image pickup means, the person retrieval processing based on biometric information is performed in the order of generation of a request for the person retrieval (in the order in which the biometric information extracted from an image taken by a camera is obtained). In this processing, when the person retrieval request is frequently generated, or when an information processing ability required for the person retrieval processing is not sufficient, there is a problem that the person retrieval processing cannot be completed within a desired processing time in many cases.